early 15c., "capacity for motion, ability to move or be moved, property of being easily movable," from Old French mobilité "changeableness, inconsistency, fickleness" and directly from Latin mobilitatem (nominative mobilitas) "activity, speed," figuratively "changeableness, fickleness, inconstancy," from mobilis "movable, easy to move" (see mobile (adj.)). Socio-economics sense of "possibility of movement between different social levels" is from 1900 in sociology writing.
1983, popularized 1991 in Persian Gulf War military slang, rough acronym for high-mobility multipurpose wheeled vehicle.
common popular designation of metallic mercury, Middle English quik-silver, from late Old English cwicseolfor, literally "living silver," so called for its mobility, translating Latin argentum vivum (source also of Italian argento vivo), "living silver;" so called from its liquid mobility. See quick (adj.) + silver (n.). Similar formation in Dutch kwikzilver, Old High German quecsilbar, German quecksilber, French vif-argent, Italian argenta viva.
early 15c., "nimbleness, quickness," from Old French agilité (14c.), from Latin agilitatem (nominative agilitas) "mobility, nimbleness, quickness," from agilis "nimble, quick," from agere "to set in motion; keep in movement" (from PIE root *ag- "to drive, draw out or forth, move"). Of mental swiftness from mid-15c.
also upwards, Old English upweard, upweardes "up, upward, toward heaven;" see up (adv.) + -ward. Similar formation in Middle Low German upwart, Middle Dutch opwaert, Dutch opwaart, Middle High German ufwart. As an adjective from c. 1600 (also in Old English). Phrase upward mobility first recorded 1949; mainly restricted to sociologists' jargon until 1960s.
silver-white fluid metallic element, late 14c., from Medieval Latin mercurius, from Latin Mercurius (see Mercury). Prepared in ancient times from cinnabar, it was one of the seven metals (bodies terrestrial) known to the ancients, which were coupled in astrology and alchemy with the seven known heavenly bodies. This one probably was associated with the planet for its mobility. The others were Sun/gold, Moon/silver, Mars/iron, Saturn/lead, Jupiter/tin, Venus/copper.
The Greek name for it was hydrargyros "liquid silver," which gives the element its symbol, Hg. Compare quicksilver, which is its popular name. It has a freezing point of -39° C. The use of the word in reference to temperature or state of the atmosphere (by 1756) is from its use in thermometers and barometers.
1680s, "disorderly part of the population, rabble, common mass, the multitude, especially when rude or disorderly; a riotous assemblage," slang shortening of mobile, mobility "common people, populace, rabble" (1670s, probably with a conscious play on nobility), from Latin mobile vulgus "fickle common people" (the Latin phrase is attested c. 1600 in English), from mobile, neuter of mobilis "fickle, movable, mobile" (see mobile (adj.)).
Mob is a very strong word for a tumultuous or even riotous assembly, moved to or toward lawlessness by discontent or some similar exciting cause. Rabble is a contemptuous word for the very lowest classes, considered as confused or without sufficient strength or unity of feeling to make them especially dangerous. [Century Dictionary, 1897]
Also used of a promiscuous aggregation of people in any rank of life (1680s), and in Australia and New Zealand used without disparagement for "a crowd." Meaning "gang of criminals working together" is from 1839, originally of thieves or pick-pockets; the American English sense of "organized crime in general" is from 1927.
The Mob was not a synonym for the Mafia. It was an alliance of Jews, Italians, and a few Irishmen, some of them brilliant, who organized the supply, and often the production, of liquor during the thirteen years, ten months, and nineteen days of Prohibition. ... Their alliance — sometimes called the Combination but never the Mafia — was part of the urgent process of Americanizing crime. [Pete Hamill, "Why Sinatra Matters," 1998]
Mob scene "crowded place" is by 1922, from earlier use in reference to movies and theatrical productions; mob-rule "ochlocracy" is by 1806.